The debate on the implications of last week's terrorist atrocities in the US has provoked a typically unthinking response from sections of the political right: these were acts of pure evil to which a more assertive application of western power is the only necessary response; there are no other conclusions to be drawn and anyone who suggests otherwise is an "apologist for evil".

The proper starting point for any analysis ought to be sympathy for the victims and revulsion for the perpetrators. But it is absurd to claim, as some commentators have, that any attempt to set these events in a wider political context is tantamount to saying America "had it coming".

A mature debate will depend on our ability to separate issues of cause and effect from questions of moral responsibility. Historians have correctly identified the punitive terms of the treaty of Versailles as a factor in the rise of Hitler. That does not turn them into Holocaust deniers. Pointing out that the suppression of a legitimate civil rights movement in Northern Ireland provided the context for the emergence of the Provisional IRA does nothing to justify its 25-year campaign of murder. To explain is not to excuse.

Counter-insurgency experts have long recognised that to be operationally effective extremist organisations need the support, or at least acquiescence, of a wider community of people who don't necessarily share all their aims. Mao Zedong, the 20th century's most successful exponent of what is now fashionably termed "asymmetrical warfare", understood this dynamic very well: "The people are water, the Red Army are fish; without water the fish will die."

We will need to understand and address the deep-rooted alienation from which terrorists derive legitimacy and support in order to deny them their life-stream: tough on terrorism, tough on the causes of terrorism, if you like. If this is indeed a war, it is as much a "war of position" to retain the moral high ground and sustain the broadest base of political support as it is a "war of manoeuvre" to eliminate the enemy. That requires a political strategy in which military action is but one component.

To argue that we are powerless to change the political environment in the face of irrational fanaticism is a perverse form of defeatism. It may be true, as Jonathan Freedland argued this week, that those who masterminded these atrocities cannot be appeased since they seek nothing less than the complete destruction of the state of Israel. But it is surely obvious that their ideas would find less resonance among a wider Arab audience if the search for a workable and just solution had not been frustrated by a combination of Israeli intransigence and western indifference. Fortunately, President Bush seems to understand this point rather better than some British commentators, which is why he has been prepared to exert unprecedented pressure to restart negotiations between Israel and the Palestinians.

More sensible voices on the right, such as Chris Patten, have also been willing to ask searching questions about relations between the developed and developing worlds. The impression that the global economy is run for the benefit of a cabal of wealthy industrialised countries leaves much of the developing world feeling used and exploited. A laissez-faire, sink or swim approach to trade and capital flows must be replaced by the spirit of benign internationalism that led to the Bretton Woods conference and the Marshall Plan.

This is not only a question for America. One of the greatest injustices in the world trade system is the refusal of the European Union to open its market to agricultural produce from developing countries that remain open to our manufactured goods and investment. The next world trade round must put the developing world at the centre of its agenda.

There also needs to be a rethink of relations with the Islamic world. It is no coincidence that Osama bin Laden draws so many supporters from countries such as Saudi Arabia and Algeria. Too often our engagement with the Muslim world has consisted of support for despotic regimes against their own people. The lesson of Algeria is that each time political expressions of Islam are suppressed they reappear in more militant form.

The great fear that this week Washington would withdraw into isolationism and unilateralism has proved unfounded. There has instead been a refreshing desire to engage and consult on the part of an administration that realises the challenge it faces requires political as well as military responses. In this it has shown greater maturity than many of its cheerleaders on the British right.